Culture
Easily grown in average, dry to medium, well-drained soils in full sun to part shade.
Noteworthy Characteristics
Onosmodium molle is commonly called false gromwell because of a perceived similarity in appearance to some of the gromwells (Lithospermum). This species is a coarse, hairy, somewhat weedy, woody-based perennial that is native from New York to Louisiana and New Mexico north to Saskachewan. It is typically found growing in rocky prairies, glades, thickets and open rocky woods/fields. It grows in an upright shrubby clump to 2-3’ tall, and is noted for its terminal, drooping, bracteose flowering spikes and white nutlets that follow the flowers. Tubular flowers appear in late spring to early summer, featuring 5 creamy white to yellowish-green petals and a distinctive style that extends beyond the end of the flowering tube. Hard white nutlets follow the flowers. Nutlets usually persist on the dead foliage throughout the winter. Nutlets give rise to the additional common name of marbleseed for plants in this genus. Sessile, ovate to lance-shaped leaves.
Subsp. occidentale is a Missouri native that is native from Manitoba to Illinois south to Texas. It typically occurs in rocky prairies, glades, thickets and open rocky woods/fields (Steyermark) and is a somewhat weedy, hairy-stemmed, hairy-leaved, woody-based perennial. Stems and leaves of this subspecies are distinctively hairy. Synonymous with Onosmodium occidentale.
Genus name means resembling the genus Onosma.
Problems
No serious insect or disease problems.
Uses
This plant is of questionable use to the ornamental landscape. It is generally not carried by nurseries and may need to be purchased through native palnt organizations or grown from seed collected from the wild. Interesting addition to prairies, open woodland areas or native plant gardens.